Mannan Castle

Mannan is a motte and bailey style castle, on a drumlin ridge running north-west to south-east. Unusually, Mannan has a double bailey and is considered to be the most impressive medieval earthwork in the country. The motte, a mound or raised hill on top of which the castle sat, is a truncated conical mound with a rectangular flat top. The stone work of the castle is encased on the top of this motte. The motte is surrounded by a fosse, with a top width of 24m, and outer bank, from which the fosse was made, 11.8m wide at the base. The bailey, an inner courtyard at the base of the motte, shows the presence of a stone wall defence and also a bank. The sub-rectangular bailey is 74m by 83m WNW/ESE and 32m by 52m north to south. The second bailey is identified by the scarps, or ditches to the north, south and east.

Excavations were carried out in 1910 by Henry Morris, who was much scuppered by the overgrowth. In 1994 permission to clear the site of overgrowth was given, which paved the way for a detailed archaeological survey.

Amongst the findings was an outer bailey that was used for intensive ironworking activity, with the presence of iron slag, iron nails, etc. The outer bailey had a defensive palisade. In the ditch between the two baileys were found the foundations of a wooden bridge connecting the inner and outer baileys. There was an earthen and timber-made castle sitting on top of the motte in 1197. By 1244 the motte and inner bailey were encased in stone.

In the mythological history of early Ireland, this site in the 4^th century was the centre of power of the Three Collas, grandsons of the High King of Ireland Cairbre Lifechair. Their maternal grandfather was king of Alba, Udhaire. The Three Collas, Cairell Colla Uais, Muiredach Colla Fo Chrí and Áed Colla Menn, were exiled to Scotland by Muiredach Tirech after murdering his uncle, Fíacha Sroiptine. In time the three brothers returned and were held in the service of Muiredach Tirech. When the time came for the brothers to have their own territory, they conquered Ulster, burning Emain Macha. This resulted in the Collas gaining mid-to-south Ulster, Airgíalla (Oriel).  Muiredach Colla Fo Chrí held Airgíalla and, over many centuries later, his descendants were O’Carroll’s Kings of Oriel.

After the Anglo Norman invasion in the 12^th century, Murrough O’Carroll submitted to Henry II in 1172. Prince John had met with Murrough O’Carroll in 1185 and accepted that O’Carroll was the ruler of Oriel, but O’ Carroll’s successor would see nothing of the lands of Oriel. Prince John had granted O’Carroll’s lands to Gilbert Pipard and Bertram de Verdon. Murrough O’Carroll died in 1189 at Mellifont Abbey. The successor to Oriel was Mahon O’Carroll, who attempted to assay the incursions of Pipard and de Vernon. In Mahon O’Carroll’s final attempt to hold his lands of Oriel, in 1193 he was captured, blinded and hung. The earthen and timber castle sitting on top of the motte in 1197 was that of Mahon O’Carroll, last King of Oriel.

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This national monument is protected in accordance with the National Monuments Acts 1930 to 2014